Gas turbines are very commonly located at synthesis gas production sites. In this regard, commonly, the fuel for both the gas turbine and the hydrocarbon containing reactant fed for the synthesis gas production is natural gas. Where such installations exist, the gas turbines are not normally thermally linked to the synthesis gas production. In integrated gasification combined cycles, however, the gas turbine and the synthesis gas production are both thermally and operationally linked in that the fuel to the gas turbine is the synthesis gas and the synthesis gas is reheated through heat transfer with the synthesis gas stream being produced.
Cogeneration is the simultaneous production of both useful thermal energy (usually steam) and electrical energy from one source of fuel. Typically, one or more gas turbines are followed by a waste heat boiler using natural gas as fuel for both the turbines and to heat the exhaust gases from the turbines.
The steam generated by the heat recovery steam generator may be applied to an auxiliary steam turbine for generating additional torque, or applied to a using process which is capable of direct use of the steam without intermediate conversion to torque. The total output of a cogeneration system offers an attractive thermodynamic conversion efficiency.
In a combined cycle electric power generating plant employing one or more gas turbines and one or more steam turbines, the hot exhaust gas from each gas turbine is typically supplied to a boiler or steam generator for providing heat for producing the steam which drives the steam turbine or turbines. The various turbines drive one or more electric generators which produce electricity which is supplied by an electric utility system to various industrial, commercial and residential customers. In some combined cycle plants, further heat is supplied to the steam generator or generators by means of additional or supplemental burner mechanisms.
Supplementary firing the exhaust gas of gas turbines in front of HRSGs has been done for years to increase HRSG output. However, such firing tends to lower CC efficiency. More power is generated but at a lower overall CC efficiency due to the increasing dominance of the lower efficiency of the bottoming part of the cycle.
Synthesis gases, that is, gases that contain primarily hydrogen and carbon monoxide are produced by steam methane reforming, auto-thermal reforming, partial oxidation, either catalytic or non-catalytic. The resultant synthesis gas stream can be further processed in a water gas shift reactor to increase its hydrogen content and the hydrogen can be separated from the synthesis gas to produce a hydrogen product stream though pressure swing adsorption.